In the making of hand-carved wax ring patterns for subsequent investment casting in precious metals it is customary for the jeweler or goldsmith to start with a wax ring pre-form in the form of a thick walled cylinder or ring-shaped cylinder. These wax ring pre-forms are supplied to the trade as cylinders approximately 8 inches long and having a bore diameter, smaller than the smallest practicable ring size--typically 0.605".
In the past, the procedure has been for the jeweler or goldsmith to cut the required length of wax (the width of the desired ring pattern) from the wax ring pre-form cylinder and to then proceed to hand enlarge the bore to the required ring size by filing and scraping the wax from the bore. This is a time consuming and tedious operation and it is difficult for the artisan to maintain perfect concentricity.
Because of the semi-crystalline nature of waxes, particularly the harder waxes employed for making ring pre-forms, cutting or trying to bore the pre-form to the required dimension using conventional metal or wood working cutting tools is not practical. The tools tend to jam in the wax because they take too big a `bite` or fracture the wax for the same reason. Conventional tools cannot be employed for a more basic reason; they are not made in the sizes which jewelers employ to measure fingers for rings. A ring is sized to a client's finger by employing ring gauges which are a series of rings of graduated sizes, arbitrarily numbered from 1 to 13 with half and quarter sizes, and fitting the ring gauges on the finger until a ring gauge is found that is comfortable and readily fits the particular finger on which the client desires to wear the ring. A tapered mandrel bearing numbers corresponding to the ring gauges is then employed by the jeweler or goldsmith to size the interior of the wax ring pattern. Regrettably the ring gauges and mandrels furnished by different manufacturers may not be completely interchangeable and each jeweler or goldsmith generally employs a single set comprising the ring gauges and the mandrel furnished by one manufacturer thereof.
Because the ring mandrel is tapered, when the jeweler or goldsmith is sizing the wax ring pattern, cut from the wax ring pre-form, with hand tools he must fit and refit the wax pattern on the mandrel after each scraping or filing operation to assure that he is finally obtaining a size that just fits the ring size marking on the mandrel, a time consuming process.